It is well known, for example, from U.S. Pat. No. 1,829,559, to form cigarettes of two or more different types of smoking materials, wherein one type of smoking material predominates in an inner core while another type of smoking material predominates in an outer annulus totally surrounding and enclosing the core.
It is also well known that a substantial proportion of the tobacco smoke entering a smoker's mouth results from the burning of tobacco in the peripheral regions of the cigarette. It is estimated that about 80% of the volume of smoke entering the smoker's mouth originates from only about 50% of the weight of tobacco in the cigarette.
It is further well known that, when a cigareete is first lit up, smoke from the burning of tobacco material in the whole cross-section of the cigarette is drawn into the smoker's mouth and not predominantly from the buring of annulus material, thereby producing a different taste for the smoker upon lighting up.
In copending U.S. patent application Ser. No. 862,702 filed May 13, 1986, assigned to the assignee hereof and the disclosure of which is incorporated herein by reference, there is described a cigarette in which additional quantities of the annulus material are provided in the lighting end of the cigarette, so that, upon the cigarette being lit, the smoke reaching the mouth of the smoker is derived mainly from annulus material. In this way, little or no change in the taste of the tobacco smoke is perceived by the smoker as the burning proceeds from light up to continued smoking.
In my copending U.S. patent application filed simultaneously herewith entitled "Linear Layered Cigarette", assigned to the assignee hereof and the disclosure of which is incorporated herein by reference, there is described a novel cigarette structure in which two outer strips or layers of higher flavour/tar ratio shredded tobacco lamina material sandwich an intermediate layer of lower flavour/tar ratio shredded lamina material at the same or similar tar level, which enables overall manipulation of flavour and tar in a cigarette to be effected.
As described therein, in one procedure, highly flavoured tobacco is trimmed from one side of the cigarette and is recirculated in the cigarette-making machine to provide the tobacco layer on the opposite side of the rod. Dense ending techniques may be employed to provide an increased quantity of the highly-flavoured tobacco at the end of the cigarette.
Conventional dense ending techniques include the use of a rotary cutter for trimming which has a pocket or notch in it so as to trim a lesser thickness of tobacco as the cigarette end segment of the rod passes the trimmer. Instead of varying the height of the tobacco trimming location, the tobacco segment just prior to the trimming point may be compressed, for example, with a rotary compression device having lobes which mechanically compress the tobacco towards the rod-carrying surface.